The present invention generally relates to a transition between a ring data transfer architecture and a bus data transfer architecture. More particularly, the present invention relates to a ring-bus transition wherein the electronic signals carried by a ring architecture are coupled or xe2x80x9cbridgedxe2x80x9d onto a large bus architecture.
Numerous commercial and military applications require switching and/or routing large quantities of information. This is especially true for satellite-based applications. For example, a commercially viable satellite needs to support information rates of up to or greater than 10 gigabits per second to perform competitively. In satellite applications particularly, a need exists for an architecture to perform this switching while minimizing the size, weight, and power of the switch. Additionally, the architecture must provide a high degree of reliability.
Both ring communication architectures and bus communication architectures exist in the art. In a ring architecture, a number of communication nodes are connected in sequence, often with a connection from the last node back to the first node to complete the ring. Each node shares a single communication link with the previous node in the sequence and a single communication node with the next node in the sequence. Each node receives data from previous nodes and re-transmits this data, along with any new data it may be adding, to the next node in the sequence.
In a bus architecture, signals are broadcast to all the nodes on the bus at the same time. Each node monitors the broadcast signals and receives only signals intended for that node. By broadcasting to all nodes, the bus architecture eliminates the re-transmission and inter-node communication of a ring architecture.
A satellite includes a number of input nodes receiving signals and a number of output nodes transmitting signals. Signals may be transmitted to and from the earth or another satellite, for example. For the received signals to travel to their desired outputs, they must be routed. In the past, ring or bus architectures, for example have been employed to route received signals. However, both rings and buses have disadvantages when implemented in a satellite environment.
Forming a single large ring with all inputs and outputs requires a great deal of power, which is at a premium in satellite applications. Additionally, such a system requires greater bandwidth than is presently feasible with a ring system. Conversely, implementation of a bus architecture sufficient to provide the desired bandwith yields a bus that is far to large and weighty to be installed in the space environment.
Prior systems use crossbar or similar switches to overcome these limitations. However, crossbar switches may be technically challenging to build and control and may also suffer from performance issues (e.g., switch contention). Additionally, the crossbar system may be difficult to scale to high capacity switching. Also, reliability (including fault tolerance) issues are difficult and/or costly to solve and implement. Finally, the crossbar switch may become weighty at large capacity. For example a typical Input/Output harness (connecting input and output units) may weigh 100 lbs. or more.
Thus, a need has long existed for a switching architecture that provides a high information rate while minimizing the size, weight, and power of the switch and providing a high degree of reliability.
The present invention provides a ring-bus transition for switching signals between inputs and outputs. The ring-bus transition receives signals from at least two inputs. Each input is coupled to a demodulator and each demodulator is coupled to a communication ring. The communication ring is coupled to a bridge which bridges the signals onto a communication bus. The communication bus is coupled to a number of output processors.
A commercial embodiment of the system may include 50 inputs separated into groups of five, each group forming the nodes of a ring. Thus, the system includes ten rings which are then bridged onto a single bus. The bus broadcasts the data from all of the rings to each of the fifty outputs in the preferred embodiment. The outputs recognize and receive data directed to that output. Once an output receives a data signal, the signal is stored in a memory queue. The signal may then be outputted in the order it arrived or in some other order based on a priority signal.
Additionally, each communication ring may have a connection from the bridge to the first of the inputs connected to each communication ring. Each input may then compare the signal originally coupled to the communication ring with a received signal from the communication ring. If the signals do not match, the input may re-transmit the signal or transmit an error message.
These and other features of the present invention are discussed or apparent in the following detailed description of the preferred embodiments of the invention.